1. Field of the Invention
The present invention relates to a system for changing the sound output of an internal combustion engine air induction system by suppressing unwanted noise at selected frequencies and by increasing the emission of sound at desired, preselected frequencies.
2. Related Art
In the world of automotive internal combustion engines, psychoacoustics is important because the motorist's perception of a vehicle's roadworthiness is greatly influenced by the sound of the engine within a vehicle. In other words, motorists listen to their engine as an indication of not only the engine's health, but also the power output of the engine. Needless to say, it is disadvantageous to install a powerful engine in a car or truck, only to have poor sound quality which fails to adequately convey to the driver and passengers the engine's capabilities. And, in any event, it is desirable to suppress sound at certain frequencies to obtain a pleasing sound characteristic, or signature, for an engine. Automotive designers have used Helmholtz resonators in the past to obtain desired induction system tuning. However, such resonators were frequently branched from air induction pipes at odd locations, creating a very odd appearance, with structures which were difficult to package within the confines of the underhood environment of a vehicle.
It would be desirable to provide a noise treatment system for an air induction system of an internal combustion engine, particularly an automotive internal combustion engine, in which the various components of the system are packaged within a single housing which efficiently not only tunes induction sound by suppressing undesired frequencies, but also provides at least a portion of a system promoting desirable frequencies, while minimizing flow losses through the sound treatment device.